Interlocking loop coupling/decoupling system for deploying vascular implant devices

ABSTRACT

In a system and method for deployment of an implant device, the implant device includes a first loop at its proximal end, and a deployment tool has a second loop attached at its distal end. A release wire slidably disposed within the deployment tool has a distal end extending through the first and second loops to releasably couple the implant device to the deployment tool, and a proximal portion extending from a proximal end of the deployment tool, which is held in a retraction device. The retraction device is operable to hold the proximal end of the deployment tool and to pull the release wire proximally through the deployment tool until the distal end of the release wire is withdrawn from the first and second loops to decouple the implant device from the deployment tool.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit, under 35 U.S.C. 119(e), of U.S.Provisional Application No. 62/584,047; filed Nov. 9, 2017, thedisclosure of which is incorporated herein by reference in its entirety.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND

The present disclosure pertains to the deployment of vascular implants,such as vascular occlusion devices, and related methods. Morespecifically, this disclosure relates to systems, devices, and methodsfor the deployment and release of a vascular implant device at a targetvascular site.

In certain implant procedures, such as those used for occlusion of avascular lumen or other bodily lumen, an implant device is inserted intothe body and released at a target site in the lumen. For example, avascular occlusion implant device can be inserted intravascularly toclose or seal blood vessels or close defects in the heart. To insert theimplant device, the implant device may advantageously be detachably orreleasably coupled to the end of a deployment tool and deployedintravascularly through a delivery device, such as a microcatheter.After placement of the implant device at the target site, the implantdevice is released or detached from the deployment tool by a suitablerelease mechanism, and the deployment tool is free to be withdrawn.

It is important that the release or detachment of the implant device bedone with the application of minimal axial force to the implant device,so as to minimize the movement of the device from its optimal locationat the target vascular site. To this end, release mechanisms have beendevised that use, for example, a thermally-fusible link that breaks inresponse to the application of heat energy through, e.g., electriccurrent. Other release mechanisms use a link that is severed by ashearing or cutting implement. While these mechanisms may achieve, tovarying degrees, the object of minimizing the transmission of axialforces to the implant device, they are frequently complex and costly tomanufacture, and/or cumbersome to use.

Furthermore, conventional intravascular implant deployment tools requireengagement of a release wire through all phases of movement needed fordecoupling the implant from the deployment tool. However, this meansthat in addition to the release wire being retracted by actuation of thedeployment tool, the release wire can also be pushed by the deploymenttool.

Accordingly, it is still a goal in the relevant arts to provide animplant device release/detachment mechanism that is simple tomanufacture and easy to use, while still meeting the necessary clinicalcriteria.

SUMMARY

The present disclosure relates to embodiments of a system for decouplinga deployed implant device from a deployment tool to which the implantdevice is coupled during deployment, wherein the deployment tool withthe implant device attached to its distal end is passed through anintravascular microcatheter to a vascular target site. The disclosedembodiments include a retraction device to engage and withdraw a releasewire having a distal end that detachably couples the implant device tothe deployment tool, and a system for detachably coupling the implantdevice to the distal end of the deployment tool. Specific embodiments ofthe disclosed detachment system use interlocking loops for coupling theimplant device to the deployment tool.

In an aspect, this disclosure relates to an interlocking loopcoupling/decoupling system configured to allow a user to detach orrelease a vascular implant device from a deployment tool through asingle action on the retraction device. More specifically, the systemdisclosed herein includes an interlocking loop coupling mechanism fordetachably coupling an implant device to a deployment tool by means of arelease wire, and a release wire retraction device that retracts therelease wire so as to decouple the implant device from the deploymenttool without imparting any significant axial force to the implantdevice.

The single action retraction device of the present disclosure can avoidreinsertion of the release wire, as the retraction device does not acton the release wire in all phases of movement. Instead, the retractiondevice only acts on the release wire during retraction of the releasewire, and it allows for resetting of the retraction device for use withanother deployment tool and implant device. The systems and methodsdescribed herein are particularly useful for the endovascular deploymentof vascular occlusion implants, but they may also be useful fordeployment of stents, coils, plugs and other implant devices fortherapeutic or diagnostic benefit of a patient.

In one aspect, a system for deployment of a vascular implant inaccordance with this disclosure comprises an implant assembly having aproximal end and a distal end, with a first loop attached to theproximal end of the implant assembly; a deployment tool having aproximal end and a distal end, with a second loop attached to the distalend of the deployment tool; a release wire slidably disposed within thedeployment tool and having a proximal end and a distal end, the distalend of the release wire extending through the first and second loops toreleasably couple the implant assembly to the deployment tool, theproximal end of the release wire extending proximally from the proximalend of the deployment tool; and a release wire retraction deviceoperable to (a) hold the proximal end of the deployment tool, (b)releasably grip the proximal end of the release wire, and (c) pull therelease wire proximally through the deployment tool until the distal endof the release wire is withdrawn from the first and second loops todecouple the implant assembly from the deployment tool.

In another aspect, a method of coupling an implant device to adeployment tool and decoupling the implant device therefrom aredisclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view with a partial cutaway of a release wireretraction device for use with an interlocking loop implant couplingsystem in accordance with an aspect of this disclosure.

FIG. 2 shows a partial cross sectional view of the retraction device ina first, un-clamped, non-actuated state.

FIG. 3 shows a partial cross sectional view of the retraction device ina second, clamped, non-actuated state.

FIG. 4 shows a partial cross sectional view of the retraction device ina third, clamped, actuated state.

FIG. 5 shows a partial cross sectional view of the retraction device ina fourth, un-clamped, actuated state.

FIG. 6 shows a partial cross sectional view of the retraction device ina fifth, resetting state.

FIG. 7 shows a partial cross sectional view of the retraction device ina sixth, resetting state.

FIG. 8 shows a partial cross sectional view of the interlocking loopcoupling/decoupling system as configured prior to actuation to decouplea deployed implant device from a release wire.

FIG. 9 shows a side view of the implant device and the distal end of theinterlocking loop coupling system of FIG. 8.

FIG. 10 shows a partial cross sectional view of the interlocking loopcoupling system after decoupling.

FIG. 11 shows a side view of the implant device and the distal end ofthe interlocking loop coupling system after decoupling.

FIG. 12 shows an exemplary guide track for the guide arms around acamming ramp of the retraction device of FIGS. 1-7.

FIG. 13 shows an embodiment of the coupling system with a release wireferrule and a stop tube.

FIG. 14 shows a cross sectional view taken along line A-A of FIG. 13.

FIG. 15 shows a cross sectional view taken along line B-B of FIG. 13.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of the presently preferredembodiments of an interlocking loop implant coupling/decoupling systemwith a release wire retraction device provided in accordance withaspects of the present disclosure. It is not intended to represent theonly forms in which the presently-disclosed components, assemblies, andmethods may be constructed or used. The description sets forth thefeatures and the steps for constructing and using the embodiments of thepresently-disclosed components, assemblies, and methods in connectionwith the illustrated embodiments. It is to be understood, however, thatthe same or equivalent functions and structures may be accomplished bydifferent embodiments that are also intended to be encompassed withinthe spirit and scope of the present disclosure. As denoted elsewhereherein, like element numbers are intended to indicate like or similarelements or features.

FIGS. 1-7 illustrate a partial cutaway of an exemplary embodiment of aretraction device 10 for an interlocking loop implantcoupling/decoupling system in accordance with this disclosure. Thefigures show half of a housing 100 and cross sectional views of a guideassembly 200, an actuator 300, and a release wire guide 400. In someembodiments, the guide assembly 200 and the actuator 300 may beintegrally formed as a unit. Alternatively, the guide assembly 200 andthe actuator 300 may be separate, mechanically connected components. Theguide assembly 200 and the actuator 300 can be understood as beingsymmetrical along an axis extending from a distal or front end 110 to aproximal or rear end 112 of the retraction device 10. (The terms“distal” and “proximal,” as used in this disclosure, are taken from theperspective of the user of the device 10.) Accordingly, the other halves(not shown) of the guide assembly 200 and the actuator 300 can beunderstood as being reflective of the halves shown in FIGS. 1-7. Forease of assembly, the housing 100 may advantageously be made of twoaxial halves that are joined together after installation of the interiorcomponents by adhesive or other suitable bonding/welding means. For thispurpose, each housing half may have complementary male locating pins 106and female locating sockets 107. A suitable durable plastic or polymericmaterial is preferred for the housing, although it may also be made of asuitable metal or alloy. Embodiments of the retraction device 10 can bemade with components formed by manufacturing processes such as injectionmolding or machining. Alternatively, formation processes such as 3Dprinting can also be used. The housing 100, when fully assembled, shouldadvantageously be externally dimensioned and configured as a handpiecethat can be comfortably and securely held and manipulated when thedevice is used.

The housing 100 of the retraction device 10 contains the guide assembly200, an interior body 302 of the actuator 300, and the release wireguide 400. The actuator 300 and the guide assembly 200 are moveableaxially relative to the housing 100 between a distal position and aproximal position by manipulation of a finger grip 304 on the exteriorof the housing 100. Specifically, the interior body 302 of the actuator300 is connected to the finger grip 304 by a connection portion or stem306 that extends through a longitudinal slot 308 in the top of thehousing 100. The guide assembly 200, in turn, is connected to theinterior body 302 of the actuator 300 so as to be moveable therewith.The top of the housing 100 is provided with a planar track surface 104on which the finger grip 304 is slidably seated. The slot 308 and thetrack surface 104 are configured to define a path for longitudinalmovement of the guide assembly 200 and the actuator 300 relative to thehousing 100. The guide assembly 200 may comprise side walls 200 a, abottom wall or base 200 b, and a top wall 302, which together generallydefine a central space for the operational components of the guideassembly 200, as will be described below.

In embodiments of the retraction device 10, the guide assembly 200 mayinclude a guide groove or track 120 providing a guide path around acamming ramp 128, a guide lever 210, and a fixed release wire grippingelement 220, which may be termed an “anvil.” (It is understood that acorresponding guide track 120 is provided in the unshown other half ofthe housing 100.) The anvil 220 may be attached to at least one of theside walls 200 a and the top wall 302 of the guide assembly 200. Theanvil 220 can be aluminum or a similar metal, or it can be a durablepolymeric or composite material. The guide lever 210 can be rotatablypinned to at least one of the side walls 200 a of the guide assembly 200with a hinge pin 211 near its distal end. The guide lever 210 canfurther comprise a movable gripping element 212, which be provided as aninsert in the guide lever located near the distal end of the guide lever210 and configured so that the movable gripping element 212 may movetoward and away from the anvil 220 as the guide lever 210 pivots (asdescribed below), whereby the proximal end of a release wire 802extending from the end of a deployment tool sheath 800 inserted into thedistal end 110 of the housing 100 can be gripped between the movablegripping element 212 and the anvil 220. The movable gripping element 212can be an insert in the guide lever 210, as shown, or it may be integraltherewith. It may have any suitable shape for providing a secure butreleasable engagement with the guide wire against the fixed grippingelement or anvil 220.

The guide lever 210 has a free proximal end terminating in a pair ofguide arms 216 (only one of which is illustrated), each of which isseated in the guide track 120 in the corresponding housing half. Theguide lever 210 is upwardly biased by a guide lever biasing spring 214(FIGS. 2-7), and it is guided for movement along a continuous closedpath provided by the guide tracks 120 within which the arms 216 areseated to move as the actuator 300 and the guide assembly 200 are movedto their different positions, as described below with reference to FIGS.2-7.

As best shown in FIG. 1, the guide assembly 200 can further include aspring support 204 extending proximally from the top wall 302. Anaxially-oriented forward biasing spring 700 can be arranged to have afirst end encircle the spring support 204 and abut a spring seat formedby the juncture of the spring support 204 and the top wall 302. Theforward biasing spring 700 extends proximally through a spring chamberdefined between an upper chamber wall 114 a and a lower chamber wall 114b, and it terminates in a second end seated on a proximal spring seat115. In this way, the forward biasing spring 700 provides adistally-directed biasing force against the guide assembly 200, therebybiasing the guide assembly 200 against moving rearward (i.e.,proximally) in the housing 100.

The distal end 110 of the housing 100 includes a distal opening 111through which the deployment tool 800 containing a release wire 802 mayenter the release wire guide 400 of the retraction device 10. Thedeployment tool 800 may be, in embodiments of the disclosure, a sheaththrough which the release wire 802 is axially and slidably disposed.(For the purposes of this discussion, the deployment tool will bereferred to as a “sheath,” although other configurations for deploymenttool may be used.) The release wire guide 400 may advantageously have acone-shaped entry 402 tapering inwardly and proximally to an axialpassage 404. This tapering shape allows the sheath 800 with the releasewire 802 to be inserted by a user while then being positioned forinsertion through the guide assembly 200. The sheath 800 mayadvantageously be retained within the passage 404 by a sheath retentiondevice 450, such as a ball-nosed spring plunger or other similarretention element or mechanism housed in a proximal portion 410 of therelease wire guide 400, that provides a radial retention force againstthe sheath 800, whereby the proximal end of the sheath 800 is held in afixed position as the release wire 802 is pulled proximally through itby the retraction device 10, as described below. In some embodiments,the sheath retention device 450 can be an integral unit, such as aspring plunger of the type marketed by Vlier Products (www.vlier.com).In other embodiments, the sheath retention device 450 can compriseseparate components, such as a ball bearing, a spring, and a set screw.The release wire guide 400 can be a separate component from the housing100, or it can be integrally molded with the housing 100. The sheathretention device 450 can be attached to the release wire guide 400 by athreaded connection or by alternative means, such as adhesive,fasteners, or other suitable ways.

FIGS. 2-7 illustrate partial cross sectional views of the retractiondevice 10 at various stages in an actuation cycle for proximal movementof the release wire in a linear fashion by manual manipulation of theactuator 300. The operation described below is defined in a sequence ofsteps or stages, each of which corresponds to a position of the actuator300 and the guide assembly 200, particularly the positions of the guidearms 216 in the guide track 120. The path defined by the guide track 120that is followed by the guide arms 216 defines a closed loop shape thatmay be, for example, generally ovoid, oblong, trapezoidal, rhomboidal,rectangular, or triangular. In the illustrated exemplary embodiment, theguide track 120 has a generally trapezoidal shape. In operation, themovable gripping element 212 can be disengaged from the release wire 802at a most distal position and at a most proximal position of the path.The movable gripping element 212 can be engaged with the release wire802 at intermediate positions of the path between the most distalposition and the most proximal position.

FIG. 2 illustrates the retraction device 10 in a first, non-actuatedstage that is considered an “at-rest position.” In this first stage, theguide arms 216 are positioned at a first or starting position 122 b inthe guide track 120, wherein the starting position 122 b is between alower distal portion 122 a and an upper distal portion 122 c of theguide track 120. In this first stage, the actuator 300 is in a forward(distal) position, and the forward biasing spring 700 is biasing theguide assembly 200 forward (distally). Additionally, the guide leverbiasing spring 214 is biasing the guide lever 210 upward towards theactuator 300. The combined forces of the forward biasing spring 700 andthe guide lever biasing spring 214 results in the guide arms 216contacting and stopping at the starting position 122 b in the guidetrack 120. At this point, in some embodiments, the guide lever 210 ispositioned so that the movable gripping element 212 does not contact aproximal portion of the release wire 802 that is extending proximallyout of the sheath 800.

FIG. 3 illustrates the retraction device in a second, clamped, butnon-actuated stage, in which the actuator 300 is moved rearwardly(proximally) by a user to a first intermediate position along the toptrack surface 104. In this position, the guide assembly 200 has movedrearwardly (proximally), such that the guide arms 216 are shifted awayfrom the starting position 122 b of the guide track 120, therebyallowing the guide lever biasing spring 214 to urge the proximal end ofthe guide lever 210 upward as the guide arms 216 track toward upperdistal portion 122 c of the guide track 120. In this state, the rearwardmovement of the actuator 300 and the guide assembly 200 compresses theforward biasing spring 700. As the guide lever 210 is urged upward, therelease wire 802 is gripped between the movable gripping element 212 andthe anvil 220, and the release wire 802 begins to be retractedrearwardly (proximally) into the housing 100 proportionately as theguide assembly 200 is moved proximally with the actuator 300.

FIG. 4 illustrates the retraction device in a third, actuated stage, inwhich the actuator 300 is further moved rearwardly (proximally) by auser to a second intermediate position along the top track surface 104,rearward (proximal) from the first intermediate position shown in FIG.3. In this position, the guide assembly 200 has moved rearwardly(proximally), such that the guide arms 216 are now positioned at a firstor upper proximal portion 126 of the guide track 120 and at a proximalend of the camming ramp 128. In the illustrated exemplary embodiment, inwhich the guide track 120 has a generally trapezoidal shape, rearwardmovement of the guide lever 210 results in the guide arms 216 beingpositioned at the first proximal portion 126 of the guide track 120,while the distal end of the guide lever 210 (in which the grippingmovable gripping element 212 is located) is moved away from the releasewire 802. Due to the slope of the proximal portion of the guide track120, the guide lever 210 is urged downward, against the biasing force ofthe guide lever biasing spring 214, thereby removing the gripping insert212 from its engagement with the release wire 802, and thus halting theproximal movement of the release wire 802 into the housing 100. Thedistance that the release wire 802 is advanced proximally into thehousing between the second and third stages (FIGS. 3 and 4,respectively) before being halted is determined largely by the length ofthe path travelled by the guide arms 216 in the guide track 120 from thesecond distal portion 122 c to the first proximal portion 126 thereof.

FIG. 5 illustrates the retraction device in a fourth, actuated stage, inwhich the actuator 300 is at a rearmost (proximal) position along thetop track surface 104. In this position, the guide assembly 200 hasmoved rearwardly such that the guide arms 216 pass over the proximal endof the camming ramp 128 to a second or lower proximal portion 127 of theguide track 120, where by the actuator 300 and the guide assembly havereached their proximal limit of travel against the biasing force of theforward biasing spring 700. Similarly, the guide lever 210 has moveddownwardly into a lower portion of its range of travel against thebiasing force of the guide lever biasing spring 214, thereby moving themovable gripping element 212 further away from (and out of engagementwith) the release wire 802.

The guide arms 216 may move in a closed path where the longitudinal(parallel to the axis of movement of the sheath 800 and release wire802) distance L is greater than the transverse distance T, as shown inFIG. 12. In some embodiments, the ratio of the longitudinal distance tothe transverse distance (L/T) is at least 1.25 and may be betweenapproximately 1.5 and 15. In some embodiments, the path may define aclosed shape with between about 3 and 6 substantially linear sides. Anexemplary closed loop movement path 216 p of the guide arms 216 aroundthe camming ramp 128 is indicated in FIG. 12 by a broken line showingvarious positions 216′, 216″, and 216″ in the movement path.

FIGS. 6 and 7 illustrate the retraction device in a fifth, resettingstage, in which the actuator 300 and the guide assembly 200 travelforward towards the distal end 110 of the retraction device 10. When thefinger grip 304 of the actuator 300 is released, the forward biasingspring 700 urges the actuator 300 and the guide assembly in the distaldirection. Due to the geometry of the guide track 120, the guide arms216 follow a movement path below the camming ramp 128, in contrast tothe actuation stages (i.e., the third and fourth stages shown in FIGS. 4and 5, respectively) in which the guide arms 216 follow a movement pathabove the camming ramp 128. As the guide arms 216 move distally in theportion of the guide track 120 below the camming ramp 120, the proximalend of the guide lever 210 is rotated downwardly (clockwise as shown inthe drawings) against the upward biasing force of the guide leverbiasing spring 214, which is further compressed. The clockwise rotationof the guide lever 210 moves the movable gripping element 212 furtheraway from the release wire, so that the axial position of the releasewire 802 within the housing 100 is not changed or affected as theactuator 300 and the guide assembly 200 are moved distally by theforward biasing spring 700 back to the first stage illustrated in FIG.2.

FIG. 7 shows the actuator 300 and the guide assembly 200 having beenmoved back distally nearly to the position shown in FIG. 2, closer tothe distal end 110 of the retraction device 10 than is shown in FIG. 6.The guide arms 216 continue to follow a movement path below the cammingramp 128, until they reach a distal edge of the camming ramp 128. In themovement path of the guide arms 216 below the camming ramp 128, theguide lever 210 is maintained in the lower portion of its range oftravel shown in FIG. 6, with the movable gripping element 212maintaining its disengagement from the release wire 802. Furthermovement of the guide arms 216 distally in the guide track 120 resultsin the guide arms 216 clearing the distal end of the camming ramp 128.As the guide arms 216 enter the first distal portion 122 a of the guidetrack 120, the guide lever biasing spring 214 biases the guide lever 210back to the first or starting position 122 b in the guide track as shownin FIG. 2, wherein gripping element 212 is not contacting the releasewire 802. At this point, the retraction device is reset back to thefirst or at-rest stage shown in FIG. 2. During or after the resetting ofthe retraction device (i.e., once the movable gripping element releasesthe guide wire 802), the retraction device 10 may be separated from thesheath 800 and the guide wire 802, thereby allowing the retractiondevice 10, once reset, to be used in another implant device decouplingapplication.

In summary, FIGS. 2-7 illustrate a sequence of operational steps orstages of the retraction device 10, in which the retraction device 10 isoperable to retract or withdraw the release wire 802 from an implantdeployed at a target vascular site, whereby the withdrawal isaccomplished unidirectionally (i.e., proximally), without disturbing ormoving implant or subjecting the implant or the deployment tool to anysignificant axial force.

Different geometries for the guide track 120 and the camming element 128can be provided. In the illustrated exemplary embodiment, a generallytrapezoidal shape for the guide track 120 is provided, with a ramp-likecamming element 128. However, alternative guide track and cammingelement geometries can be used to achieve the result of retracting therelease wire during actuation, while allowing the guide assembly to bereset without reversing the direction of movement of the release wire802 (i.e., without advancing the release wire 802).

The fulcrum point (i.e., the pin 211) of the guide lever 210, and/or theshape of the guide lever 210, can be defined such that the movement ofthe guide arms 216 is different from that of the embodiment shown inFIGS. 2-7. For example, an embodiment may be provided in which the fixedgripping element (“anvil”) 220 and the movable gripping element 212 acton the release wire 802 when the guide arms 216 engage a bottom portionof the guide track 120 instead of the top portion. Moreover, the guidingfunction provided by the guide track 120 can be provided by a raisedwall or rib on the interior surface of the housing 100, along which eachof the guide arms 216 travels.

Also, variations for actuator can be achieved through other mechanisms.For example, a uni-directional rotating spool can be used, in which casea rotating dial may be provided for actuation by a user. Such a devicemay allow for retraction of the release wire by rotation in onedirection and slipping in the opposite direction, such as would beunderstood from a ratcheting socket wrench.

FIGS. 8-11 illustrate the retraction device 10 in combination with animplant assembly 900 releasably coupled to a deployment tool (such as,e.g., the sheath 800) by an interlocking loop coupling system. Theimplant assembly 900 can include an implant device 901 (e.g., a vascularoccluder, as shown), and an implant loop 904 that may be attached to theimplant device 901 by a crimp portion 906 at the proximal end of theimplant device 901.

FIGS. 8 and 9 illustrate the interlocking loop coupling system in anon-detached state, i.e., when the implant assembly 900 is coupled tothe deployment tool (e.g., the sheath 800) during deployment of theimplant assembly at a target vascular site. FIG. 8 illustrates theretraction device 10 engaging the proximal portion of a release wire 802extending proximally from the proximal end of a sheath 800, the distalend of which extends distally from the distal end of the sheath 800, asshown in FIG. 9. Referring still to FIG. 9, a tool loop 804 is attachedto the distal end of the sheath 800 containing the release wire 802,whereby the tool loop 804 can be placed through, or overlapped with, theimplant loop 904. The distal end or portion of the release wire 802 isextended through the tool loop 804 and the implant loop 904, therebydetachably connecting the loops 804, 904. The placement of the releasewire 802 through the loops 804, 904 thus releasably couples the implantassembly 900 to the deployment tool (sheath) 800, preventing theirseparation. In some embodiments, the crimp portion 906 may have a recessfor receiving the distal end of the release wire 802 when the tool loop804 and the implant loop 904 are coupled together as interlocking loops.Alternatively, the implant loop 904 can be provided inside the tool loop804, or the implant loop 904 and the tool loop 804 can be assembled inan overlaid fashion without either loop entering the other.

In aspects of the implant assembly 900, the implant loop 904 may be aloop extending only into the crimping portion 906, where the implantloop 904 is fixed to the implant 901 by way of crimping, welding,adhesive, or other suitable methods. In this way, the amount of materialnecessary for the implant loop 904 can be reduced, and the implant loop904 can be independently adjusted depending on the implantationtechnique. Although the exemplary embodiments use a loop, alternativegeometries can be used. For example, a braid, cable or wound loop orcoil structure within the loop can be provided.

FIGS. 10 and 11 illustrate the interlocking loop coupling system in adetached state, i.e., when the implant assembly 900 has been released ordecoupled from the sheath 800 after deployment. To detach the implantassembly, the release wire 802 is withdrawn (in the proximal direction)by means such as the retraction device 10 described above, from both thetool loop 804 and the implant loop 904. Thus, the retraction device 10(or a functional equivalent) is operated to retract the release wire802, thereby decoupling the implant loop 904 from the tool loop 804.Because the implant loop 904 and the tool loop 804 are not tied togetheror mechanically connected to each other, they are released from oneanother solely in response to the retraction of the release wire 802,thereby releasing or decoupling the implant assembly 900 from the sheath800. The decoupling of the implant assembly is thus accomplished withouta significant axial force being applied to the implant once the implantassembly is located and deployed in the target vascular site, therebyminimizing the chance of dislodgement or displacement of the implantfrom the target site.

Withdrawal of the release wire 802 from engagement with the tool loop804 and the implant loop 904, resulting in release of the implant, maybe detected by a sensor (not shown) inside the retraction device 10 thatmay indicate to the user confirmation that detachment has occurred. Thesensor may detect the proximity or contact with release wire 802 or anelement connected to the release wire. The sensor may communicatemechanically or electrically to an indicator element that is in visualor physical contact with the user or visible to the user. For example, asmall light or light emitting diode (LED) may be incorporated into theretraction device 10 that is connected to a power source and the sensorso as to indicate movement of release wire 802 sufficient for release ofthe implant.

In some embodiments, as shown in FIGS. 13-15, an overcoil 808 may extendaxially between the distal end of the sheath 800 and the proximal end(e.g., the crimp portion 906) of the implant assembly 900, therebyextending coaxially around the loops 804, 904 and the distal end of therelease wire 802 interconnecting them. The overcoil 808 may be either aunifilar or multifilar helical coil made from a metal, a polymer, or acomposite. As further shown in FIGS. 13-15, embodiments of theinterlocking loop coupling system may include a tubular or annular stop812 attached to the overcoil 808 proximally from the tool loop 804, anda tubular ferrule 810 attached to the release wire 802 proximally fromthe stop 812. The ferrule 810 and the stop 812 are configured to reducethe probability of undesirable movement of the release wire 802, asexplained below.

It may be advantageous to minimize any tortuous movement of the releasewire 802, and to avoid having the release wire 802 extend past a distalend of the overcoil 808. Specifically, it is advantageous to avoidhaving a loose end of the release wire 802 extend away from the overcoil808 or the implant assembly 900. Tortuous movement can occur, forexample, if the implant assembly 900 encounters high friction in thedelivery microcatheter. As friction increases when the user continues topush at the proximal end of the delivery device, the overcoil 808 maystart to compress. As the overcoil 808 compresses while the implantposition is axially fixed, the distal end of the release wire 802 maypotentially extend in an undesired direction. The release wire ferrule810 and the stop tube 812 help minimize undesirable movement of therelease wire 802 during movement of the delivery device and positioningof the implant assembly 900 in the target site. The ferrule 810 and thestop 812 may be made of any suitable metallic or non-metallic material,such as for example, a stainless steel, a polymer, or a composite. Theferrule 810 can be attached to the release wire 802 by any suitablemeans, such as an adhesive, or by crimping, welding, soldering, or othersuitable methods. The ferrule 810 and the stop 812 are internallydimensioned so that the tool loop 804 and the release wire 802 may movefreely within the overcoil 808. The stop 812 may be attached to an innersurface of the overcoil 808 at one or more attachment points 814, suchas by laser welding, sonic welding, adhesive, or other methods. The stop812, being distal of the ferrule 810, thereby can act as a stop to limitdistal movement of the ferrule 810. As the ferrule 810 is attached therelease wire 802, the stop 812 thereby also acts as a stop to limitdistal movement of the release wire 802 relative to the loops 804, 904.

The inner diameter of the stop 812 is advantageously sized to allow thetool loop 804 and release wire 802, but not the ferrule 810, to passthrough it freely. Thus, even under high friction scenarios, the ferrule810 is pushed against the stop 812 and prevents any further distalmovement of the release wire 802 relative to the overcoil 808. Also, dueto the free passage allowed the release wire 802, the stop 812 will notimpede movement in the reverse direction, which is required for implantdetachment. The ferrule 810 is thus blocked from further advancementdistally due to its outer diameter not fitting through the innerdiameter of the stop 812.

FIG. 14 is a cross-sectional view taken along line A-A of FIG. 13,showing the arrangement of the ferrule 810 coaxially surrounding therelease wire 802. The tool loop 804 may be adjacent to the release wireferrule 810 inside the overcoil 808. FIG. 15 is a cross-sectional viewtaken along line B-B of FIG. 13, showing the arrangement of the stop 812inside the overcoil 808. Both the tool loop 804 and the release wire 802may be inside the stop 812. That is, the stop 812 coaxially surroundsboth the tool loop 804 and the release wire 802.

An implant coupling/decoupling system in accordance with the subjectmatter of this disclosure may be operated as follows:

A release wire is provided that is slidably disposed within a deploymenttool having a proximal end a distal end terminating in a first loop, therelease wire having a proximal end that extends proximally a shortdistance from the proximal end of the deployment tool, and a distal endthat passes through the first loop and a second loop at the proximal endof the implant device so as to releasably couple the implant device tothe distal end of the deployment tool. The proximal end of thedeployment tool is introduced into a distal opening of a release wireretraction device and is fixed within the retraction device with theproximal end of the release wire extending proximally from the proximalend of the deployment tool. The retraction device is operated to (1)grip the proximal end of the release wire, (2) pull the release wireproximally through the deployment tool to withdraw the release wire fromthe first and second loops, thereby decoupling the implant device fromthe deployment tool, and (3) disengage from the release wire afterproximal movement of the release wire.

In another aspect, the method according to this disclosure may comprise:(1) providing a deployment tool having a first loop attached to itsdistal end; (2) providing an implant device having a second loop at itsproximal end; (3) passing a release wire axially through the deploymenttool so that a distal end of the release wire passes through the firstand second loops to releasably couple the implant device to thedeployment tool, and so that a portion of the release wire is exposed atthe proximal end of the deployment tool; (4) gripping the exposedportion of the release wire; and (5) pulling the release wire proximallythrough the deployment tool until the distal end of the release wire iswithdrawn from the first and second loops to decouple the implant devicefrom the deployment tool.

Although exemplary embodiments of the subject matter of this disclosurehave been specifically described and illustrated herein, manymodifications and variations will be apparent to those skilled in theart. Accordingly, it is to be understood that the retraction device andthe interlocking loop coupling system, their respective components, andrelated methods as disclosed herein may be embodied other than asdescribed herein. It will also be appreciated that the interlocking loopcoupling system described above is well-suited for use with thepreviously-described release wire retraction device. Accordingly, it iscontemplated that there will be many applications and situations inwhich they will be used together in implant device deployment systemsand methods in which the implant device is deployed by means of arelease wire. In other applications and situations, however, it may beadvantageous either to use the interlocking loop coupling systemdescribed above with other types of retraction devices, or theabove-described retraction device with other types of implant/releasewire coupling systems and arrangements.

What is claimed is:
 1. A system for deployment of a vascular implantdevice, comprising: a first loop attached to a proximal end of theimplant device; a deployment tool having a proximal end and a distalend, with a second loop attached to the distal end of the deploymenttool; a release wire slidably disposed within the deployment tool andhaving a proximal end and a distal end, the distal end of the releasewire extending through the first and second loops to releasably couplethe implant device to the deployment tool, the proximal end of therelease wire extending proximally from the proximal end of thedeployment tool; and a release wire retraction device operable to pullthe release wire proximally through the deployment tool until the distalend of the release wire is withdrawn from the first and second loops todecouple the implant device from the deployment tool.
 2. The system ofclaim 1, wherein the retraction device is configured to (a) hold theproximal end of the deployment tool, (b) releasably grip the proximalend of the release wire, and (c) pull the release wire proximallythrough the deployment tool.
 3. The system of claim 2, wherein therelease wire retraction device comprises: a housing having a distalopening configured for receiving a proximal portion of the deploymenttool including the proximal end thereof; a gripping assembly in thehousing and configured for releasably gripping the proximal end of therelease wire; a guide assembly movably mounted in the housing between adistal position and a proximal position, and operatively connected tothe gripping assembly to move the gripping assembly between engagementwith and disengagement from the proximal end of the release wire; and anactuator having an external portion configured for manipulation distallyand proximally by a user, and an internal portion operatively connectedto the guide assembly for moving the guide assembly between the distalposition and the proximal position.
 4. The system of claim 3, whereinthe guide assembly is operatively connected to the gripping assembly toengage the proximal end of the release wire when the guide assembly isin an intermediate position, and to disengage from the proximal end ofthe release wire when the guide assembly is in the proximal position. 5.The system of claim 3, wherein the gripping assembly comprises a fixedgripping element fixed in position in the housing, and a movablegripping element operatively connected to the guide assembly to be movedbetween a position of engagement with the proximal end of the releasewire when the guide assembly is in an intermediate position and aposition of disengagement from the proximal end of the release wire whenthe guide assembly is in the proximal position.
 6. The system of claim3, wherein the guide assembly is spring-biased toward the distalposition.
 7. The system of claim 5, wherein the guide assemblycomprises: a lever having a first end in which the movable grippingelement is disposed, and a second end movably seated in a guide pathdefined in the guide assembly, wherein the guide path is configured tomove the lever so as bring the fixed gripping element into engagementwith the proximal end of the release wire as the guide assembly is movedproximally, and to move the lever to disengage the fixed grippingelement from the proximal end of the release wire as the guide assemblyis moved distally.
 8. The system of claim 7, wherein the guide path isconfigured as a closed loop.
 9. The system of claim 7, wherein the guidepath is defined by a track, and wherein the second end of the lever isconfigured as a guide arm movably engaged with the track.
 10. The systemof claim 1, further comprising an overcoil extending axially between thedistal end of the deployment tool and the proximal end of the implantdevice.
 11. The system of claim 10, further comprising: a stop attachedto the overcoil; and a ferrule attached to the release wire, the ferrulebeing arranged proximally of the stop to limit distal movement of therelease wire 802 relative to the second loop.
 12. The system of claim11, wherein the stop has an inner diameter and the ferrule has an outerdiameter greater than the inner diameter of the stop.
 13. A method ofcoupling a vascular implant device to a deployment tool, comprising:providing a first loop at a distal end of the deployment tool; providinga second loop at a proximal end of the implant device; and passing arelease wire axially through the deployment tool so that a distal end ofthe release wire passes through the first and second loops to releasablycouple the implant device to the deployment tool, and so that a proximalportion of the release wire is exposed at the proximal end of thedeployment tool.
 14. A method of deploying a vascular implant device ata target vascular site using a deployment tool passed intravascularly tothe target vascular site, comprising: providing a first loop at a distalend of the deployment tool; providing a second loop at a proximal end ofthe implant assembly; passing a release wire axially through thedeployment tool so that a distal end of the release wire passes throughthe first and second loops to releasably couple the implant device tothe deployment tool, and so that a proximal portion of the release wireis exposed at the proximal end of the deployment tool; gripping theexposed portion of the release wire; and pulling the release wireproximally through the deployment tool until the distal end of therelease wire is withdrawn from the first and second loops to decouplethe implant device from the deployment tool.
 15. The method of claim 14,wherein the steps of gripping the exposed portion of the release wireare performed by a release wire retraction device, wherein the step ofgripping the exposed portion of the release wire is performed byinserting the proximal end of the deployment tool into the release wireretraction device and fixing the proximal end of the deployment tool inplace within the retraction device with the exposed portion of therelease wire extending proximally from the proximal end of thedeployment tool, and wherein the step of pulling the release wireproximally is performed by releasably gripping the exposed portion ofthe release wire and pulling it proximally through the deployment tool.16. The method of claim 14, wherein the gripping step is performed by agripping assembly movable between a position of engagement with theexposed portion of the release wire and a position of non-engagementwith the exposed portion of the release wire, and wherein the step ofpulling the release wire proximally is performed by: (a) moving thegripping assembly proximally while the gripping assembly is in theposition of engagement to pull the release wire proximally a distancesufficient to withdraw the distal end of the release wire from the firstand second loops; (b) moving the gripping assembly into the position ofnon-engagement; and (c) moving the gripping assembly distally when thegripping assembly is in the position of non-engagement.
 17. The methodof claim 16, wherein the gripping assembly comprises a fixed grippingelement and a movable gripping element, and wherein the grippingassembly is put into the position of engagement by moving the movablegripping element toward the fixed gripping element so as to engage theproximal portion of the release wire against the fixed gripping element,and wherein the step of moving the gripping assembly into the positionof non-engagement is performed by moving the movable gripping elementaway from the fixed gripping element so as to release the proximalportion of the release wire.
 18. A device for retracting a release wirehaving a distal end releasably coupling a vascular implant device to adistal end of an intravascularly-introduced deployment tool, wherein thedeployment tool has a proximal portion from which a proximal portion ofthe release wire is exposed, the device comprising: a housing having adistal opening configured for receiving the proximal portion of thedeployment tool from which the proximal portion of the release wire isexposed; a gripping assembly in the housing and configured forreleasably gripping the exposed proximal portion of the release wire; aguide assembly movably mounted in the housing between a distal positionand a proximal position, and operatively connected to the grippingassembly to move the gripping assembly between engagement with anddisengagement from the exposed proximal portion of the release wire; andan actuator having an external portion configured for manipulationdistally and proximally by a user, and an internal portion operativelyconnected to the guide assembly for moving the guide assembly betweenthe distal position and the proximal position.
 19. The device of claim18, wherein the guide assembly is operatively connected to the grippingassembly to engage the exposed proximal portion of the release wire whenthe guide assembly is in an intermediate position, and to disengage fromthe exposed proximal portion of the release wire when the guide assemblyis in the proximal position.
 20. The device of claim 18, wherein thegripping assembly comprises a fixed gripping element fixed in positionin the housing, and a movable gripping element operatively connected tothe guide assembly to be moved between a position of engagement with theexposed proximal portion of the release wire when the guide assembly isin an intermediate position and a position of disengagement from theexposed proximal portion of the release wire when the guide assembly isin the proximal position.
 21. The device of claim 18, wherein the guideassembly is spring-biased toward the distal position.
 22. The device ofclaim 20, wherein the guide assembly comprises: a lever having a firstend in which the movable gripping element is disposed, and a second endmovably seated in a guide path defined in the guide assembly, whereinthe guide path is configured to move the lever so as bring the fixedgripping element into engagement with the exposed proximal portion ofthe release wire as the guide assembly is moved proximally, and to movethe lever to disengage the fixed gripping element from the exposedproximal portion of the release wire as the guide assembly is moveddistally.
 23. The device of claim 22, wherein the guide path isconfigured as a closed loop.
 24. The device of claim 22, wherein theguide path is defined by a track, and wherein the second end of thelever is configured as a guide arm movably engaged with the track.